I. Field of the Invention
The present invention relates generally to ergonomically designed keyboards for computers, typewriters and the like. More particularly, the present invention relates to an adjustable, curved keyboard having arcuately arranged keys that complement naturally a user's wrists, hands and fingers. This keyboard permits the user to maintain a relaxed position which does not cause repeated stress to the user's wrists, hands and fingers.
Frequent users of standard keyboards are often afflicted with a serious, repetitive stress injury ("RSI"), such as carpal tunnel syndrome. RSI is often caused by maintaining the fingers, hands, wrists and arms in an unnatural position, i.e. bent wrists, while typing. The symptoms of RSI include tingling and numbness in the fingers which progress to aching or shooting pains and weakness in the hands and forearm. RSI, particularly carpal tunnel syndrome, is a major concern for keyboard operators and their employers since such injuries cause discomfort to the operator, lower the productivity of the operator, and often increase worker compensation claims.
Physical therapists, orthopedic surgeons and ergonomics experts have suggested that the user's posture is important for prevention of RSI, particularly carpal tunnel syndrome. In addition to sitting up straight, the user's feet should be flat on the floor, elbows should be close to the body, and forearms should be substantially parallel to the floor. More importantly, the user's wrists should not be bent, and the user's hands should be in a straight line with his or her forearms. Also, the palms of the user's hands should rest on a soft surface to avoid pressure to the user's shoulders.
II. Description of the Prior Art
A standard keyboard used for a computer or typewriter is generally elongated. The depth of a standard keyboard is much less than the length, but has enough depth to provide a number of rows of alphanumeric keys and a space bar positioned below the lowermost row. The particular dimensions of a standard keyboard may vary since additional keys, such as function keys, cursor control keys and numeric keypad keys, may cause an increase in the length and/or depth of the keyboard. The height of a standard keyboard varies but conventional keyboards are commonly flat.
The flat design requires the hands and wrists to be held at an unnatural position. The natural position of a user's hands is in alignment with his or her forearms so that the user's wrists are not bent, and the user's fingers are arched slightly forward. In order to access the majority of keys of a conventional keyboard, the user must keep his or her hands parallel to the surface of the keyboard. In doing so, the wrists of a user are often bent or cocked back and upward thereby causing muscle strain through the forearms, wrists and hands. By such cocking of his or her wrists, the muscles, tendons and nerves that run through the wrist are compressed or pinched, thereby causing fatigue and strain for the user's hands.
There have been attempts to redesign keyboards to allow users a more natural wrist and hand positions during typing. One design is a planar keyboard having an arcuate shape within a particular horizontal plane so that the middle portion of the is keyboard is closer to the user's body than the end portions. To use the keyboard, the user's hands angle inward toward the keyboard instead of linearly in front of the user's body as in a conventional keyboard. The user's elbows are separated away from the body, and the hands are more directly in-line with the forearms.
Such a design is shown, for example, in U.S. Design Pat. No. Des. 338,665 to R. W. Riley, et al. titled COMPUTER KEYBOARD and U.S. Design Pat. No. Des. 348,453 to R. W. Riley, et al. titled KEYBOARD WITH WRIST PAD. Each patent provides an adjustable keyboard having a planar arcuate shape that may be changed to different radii of curvature within a horizontal plane. Thus, the keyboard is adjusted about a vertical axis to curve the ends of the keyboard away from the user. Similarly, U.S. Pat. No. 5,073,050 to S. Andrews titled ERGONOMIC KEYBOARD APPARATUS provides a keyboard having a planar arcuate shape that is adjustable within a horizontal plane to a different radii of curvature. In contrast to the two Riley patents, the keyboard ends are adjusted toward the user instead of away from the user.
A problem with the above planar arcuate keyboard is that the top surface of the keyboard is flat. Thus, like a conventional keyboard, the flat design of a planar arcuate keyboard requires the hands to be held at an unnatural position. Specifically, the user must keep his or her hands parallel to the surface of the keyboard when typing. Therefore, the user must cock his or her wrists and hands thereby experiencing muscle strain through the forearms, wrists and hands.
Non-flat or elevationally curved keyboards are also known. Such keyboards are described in U.S. Pat. Nos. 5,029,260 and 5,120,938, both to S. H. Rollason and titled KEYBOARD HAVING CONVEX CURVED SURFACE. Each keyboard has a uniform elevational curve to all rows of keys such that the middle portion is substantially horizontal, whereas the end portions are directed downward and away from the middle portion. To use the keyboard, the user's hands are substantially horizontal when typing at the middle portion but are substantially vertical when typing at the end portions.
Other ergonomic keyboards have unique curvatures and arrangements that attempt to provide the user with a comfortable typing position. For example, U.S. Pat. No. 4,597,681 to A. N. Hodges titled ADJUSTABLE KEYBOARD provides a keyboard having two sections that may be adjusted relative to each other. Each keyboard section has a concave arrangement of keys that curve toward the user. Also, U.S. Pat. No. 5,397,189 to R. F. Minogue titled NON-PLANAR ERGONOMIC KEYBOARD provides an arcuate keyboard having keys that slope toward the center of the keyboard. Also, the central keys are raised from the general horizontal plane of the keyboard to bring them closer to the user.
Similar to the planar arcuate keyboards, the elevationally curved keyboards and other ergonomic keyboards still require the hands to be held at an unnatural position. As stated above, the natural position of the user's hands is to be in alignment with the forearms with the fingers arched slightly forward. None of the above keyboards provide a typing surface that so complements naturally to a user's hands so that the user's hands and wrists are at a relaxed position thereby avoiding RSI.
The present invention is a keyboard having an arcuate top surface that is curved about a horizontal axis extending through the entire length of the keyboard, much like an upper section of an elongated cylinder. All keys in a particular row are positioned at the same elevational level, and each row is positioned at a different elevational level. When using the present invention, the user does not bend his or her wrists. The elbows are close to the body as suggested by physical therapists, orthopedic surgeons and ergonomics experts. The user's arms may be substantially straight to keep the elbows close to the body while typing comfortably at the keyboard. In addition, the user may arch his or her fingers forward at their natural position over the top surface of the keyboard.